Global data traffic explosively increases and emerging services represented by video and streaming media services are rapidly developed, such that data services having dynamic, high bandwidth and high quality requirements become main network traffic and drives networks to evolve towards grouping. In the aspect of transport networks, it can be seen that they are developed from traditional Synchronous Digital Hierarchy (SDH) circuit switching networks to SDH-based Multi-Service Transfer Platforms (MSTP) having a multi-service access function and gradually evolve into Packet Transport Networks at current, which is exactly a result of data development of network traffic. Fundamentally, circuit switching networks can only provide rigid pipes and coarse-granularity switching and cannot effectively satisfy demands for dynamic nature and burst nature of data services, while flexible pipes and statistical multiplexing features of packet switching networks naturally adapt to data services. However, packet switching in the related art is basically processed based on an electric layer, the cost is high, the energy consumption is great, the processing bottleneck is gradually prominent with the rapid increase of traffic, and it is difficult to adapt to the requirements of high speed, flexibility, low cost and low energy consumption on networks. Optical networks have the advantages of low cost, low energy consumption and high-speed great capacity. However, traditional optical circuit switching networks (such as Wavelength Division Multiplexing WDM) and Optical Transport Networks (OTNs) can only provide large-granularity rigid pipes, lack for flexibility of electric packet switching and cannot effectively bear data services.
In access networks, Gigabit-Capable Passive Optical Network (GPON) technology combines the advantages of the optical layer and the electric layer to a certain extent. In a downlink direction, it adopts an optical layer broadcasting mode to distribute downlink signals sent by an Optical Line Terminal (OLT) to each Optical Network Unit (ONU) through an optical splitter, and at the same time, a bandwidth map of an uplink frame is carried in a downlink frame header to indicate sending time and length of uplink data of each ONU; in an uplink direction, each ONU sends data according to the indication of the bandwidth map, and the data are multiplexed to a wavelength channel through an optical coupler and are uploaded to the OLT. Thereby, the GPON has the features of high speed, large capacity and low cost of the optical layer on one hand and realizes optical layer statistic multiplexing of loops of data in the uplink direction, thereby improving the flexibility and the bandwidth utilization rate. The GPON generally adopts a star/tree network topology, its working principle is suitable for bearing multipoint to single point convergent traffic (south-north traffic is dominant), and thus it is successfully applied and deployed in a large scale in access networks.
However, for non-convergent application scenarios such as metropolitan area core networks and data center internal switching networks, the ratio of east-west traffic is very great and even is dominant, and the GPON technology is obviously unsuitable (east-west traffic needs to be forwarded through an OLT electric layer and the GPON capacity is limited). The OBTN adopts an all-optical switching technology based on Optical Burst (OB), has a capability that any node of a network provides on demand and rapidly schedules inter-optical layer bandwidth, and it can dynamically adapt to and well support various traffic (such as south-north burst traffic and east-west burst traffic) scenarios, improve resource utilization efficiency and network flexibility, simultaneously reserves the advantages of high speed, great capacity and low cost, and it is applicable to various network topologies such as start, tree and ring topologies. At the same time, data channels and control channels are transmitted by adopting different wavelength, and the separate processing of control signals and data signals is very greatly facilitated.
However, optical burst switching networks in the related art all need to be configured with a Fiber Delay Line (FDL) to enable ring length to be integral times of timeslot length, nodes also need to be configured with an FDL to enable data frames and control frames to reach a relationship such as of having the same arrival time; and an optical burst packet must have a fixed length and a guard interval also has a fixed length. The configuration of the FDL will cause network design to be complex, the length control is comparatively tedious, certain losses will be caused to optical power, a great number of FDL arrays are needed to improve time precision of timeslot synchronization of nodes and this is unrealistic.